Turkey enters mourning after Ankara blasts killed almost 100
Turkey is beginning three days of mourning after two blasts at a peace rally in the capital Ankara killed at least 95 people on Saturday, the deadliest ever such attack in Turkey.
The attack left 245 people injured, with 48 of them in a serious condition.
TV footage showed scenes of panic and people lying on the ground covered in blood, amid protest banners.
The government called the blasts a "terrorist act" and angrily rejected allegations that it was to blame.
Late on Saturday, US President Barack Obama spoke to President Recep Tayyip Erdogan and "conveyed his deepest personal sympathies for those killed and injured in these heinous attacks," the White House said.
The blasts took place near the city's central train station as people gathered for a march organised by leftist groups.
The rally was demanding an end to the violence between the Kurdish separatist PKK militants and the Turkish government, and had been due to start at 12:00 (09:00 GMT).
The two explosions happened shortly after 10:00 as crowds gathered ahead of the rally. Amateur video footage showed a group of young people holding hands and singing, before the first blast.
Eyewitnesses described anger amongst the crowd being directed against the police after the blasts. One participant at the rally told the BBC that the police used tear gas "as soon as the bomb went off", and "would not let ambulances through".
Prime Minister Ahmet Davutoglu said there was evidence that two suicide bombers had carried out the attack, which comes three weeks before a re-run of June's inconclusive parliamentary elections.
President Erdogan called the attack "loathsome". He has cancelled a planned visit to Turkmenistan.
The pro-Kurdish HDP party was among those attending the rally. Its leader Selahettin Demirtas has blamed the state for the attack and has cancelled all election rallies.
Mr Demirtas condemned the government as "murderers" and said it had blood on its hands.
The party has previously blamed the government for colluding in attacks on Kurdish activists, which the government denies.
Cemalettin Hasimi, director of press and information at the prime minister's office, told the BBC that such allegations were "a disgrace, unacceptable". He insisted that authorities were determined to find those behind the attack.
No group has yet said it carried out the attack
Protesters gathered in Istanbul in the aftermath of the attack - these placards read "killer state"
Analysis: Mark Lowen, BBC News, Istanbul
After the ceasefire between the PKK and the Turkish state broke down in July, Turkey has spiralled into tit-for-tat attacks between the two sides, and tension between Kurds and Turkish nationalists has soared.
Amidst the frenzy of a repeat election in November, it was expected that something dangerous was imminent.
The pro-Kurdish HDP party has blamed the state. That is undoubtedly a reference to the so-called "deep state" often talked about here: a shady mix of nationalist forces either colluding with or supporting the government in power.
The West's vital ally in the Middle East is now facing a perfect storm: deep political polarisation, the bubble of economic success on the brink of bursting, a resumption of violence with the PKK, the threat from Islamic State, and two million Syrian refugees and counting.
The tragedy in Ankara is a sign of the dark times Turkey is now facing.
An HDP rally in the city of Diyarbakir was bombed in June, ahead of general elections in which the party entered parliament for the first time.
In July, a suicide bombing by suspected Islamic State militants on a gathering of socialist youth activists in the town of Suruc on the Syrian border killed at least 30 people.
A ceasefire between the Kurdish militant group the PKK and Turkey's government later broke down, with the PKK accusing the security forces of collaborating with IS.
This led to an increase in attacks from both sides over the summer.
On Saturday the PKK called on its fighters to halt its guerrilla activities in Turkey unless attacked first. A statement from an umbrella group that includes the PKK said its forces would "make no attempts to hinder or harm the exercise of a fair and equal election".